Rotary regenerator drum fabrication



March' 19, 1963 1. woLANsKY ETAL 3,081,822

ROTARY REGENERATOR DRUM FABRICATION COMBUSTOQ Filed April 14, 1960 Joh/z Wala/75kg 3,05L8Z2 Patented Mar. 19, 1953 hice Chio

Filed Apr. 14, 1960, Ser. No. 22,272 3 Claims. (Cl. 165-10) The present invention relates to improvements in a rotor for regenerator assemblies of the type for use with gas turbines wherein the heat energy of the turbine exhaust is used for heating the compressed air ilowing to the combustor.

The present invention contemplates the provision of an improved rotary regenerator drum having a matrix formed of an improved material with a very low expansion coelicient and capable of withstanding high thermal shock. The material also is capable of withstanding high temperatures. More particularly the regenerator matrix is formed of a ceramic material of particular characteristics. In obtaining these characteristics the strength of the material has necessarily been reduced and a feature of the invention is the provision of a structure whereby the overall unit strength is adequate for reliable regenerator use.

An object of the present invention is to provide an improved regenerator drum formed of a ceramic which has especially attractive properties for heat regenerator use and has a low basic cost for mass production.

Another object of the invention is to provide an improved matrix construction and material for a rotary regenerator which has a very low expansion coeicient, has high thermal shock resistance, good specific heat properties, excellent corrosion resistance to conventional gas turbine combustion gases, and a much lower weight than a conventional all metal regenerator drum.

A further object of the invention is to provide a matrix drum structure for a heat regenerator wherein material which in itself is incapable of withstanding the mechanical pressures can be used with relative reliability and safety.

Other objects and advantages Will becomes more apparent with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiments thereof in the specification, claims and drawings, in which:

FIGURE l is a plan view shown somewhat schematically of a regenerator mechanism of the type in which the principles of the present invention may be embodied;

FIGURE 2 is a schematic showing of a gas turbine mechanism employing a rotary regenerator;

FIGURE 3 is an enlarged fragmentary vertical sectional view taken through a regenerator drum constructed in accordance with the principles of the present invention; .and

FIGURE 4 is an enlarged detailed fragmentary elevational view taken substantially along line IV-IV of FIGURE 3.

As shown on the drawings:

As illustrated in FIGURE l, a rotary regenerator of the type in which a matrix drum constructed in accordance with the principles of the present invention may be used is shown having a housing l with a matrix drum l1 rotatably mounted therein. Extending across the housing is a partition l2 which separates the drum into separate chambers with a chamber 12a being designated as a high pressure low temperature chamber and chamber 12b as a low pressure, high temperature chamber. The matrix drum 1l rotates through the chambers and at the locations where it passes through the partition 12 seals 13 and 14 are provided. The matrix drum ll is suitably driven in rotation and supported such as by rollers l5 and i6 and two rollers may be employed at locations l5 and i6 supportingly engaging the upper and lower edges of the matrix drum `1l. The housing l0 is provided with inlet and outlet openings for each of the chambers -y12a and 12b, not shown in FIGURE l.

As illustrated in FIGURE 2, a rotary gas turbine 17 has a housing with a rotor 18 therein mounted on a shaft i9. Combustion gases for driving the turbine are received from a combustor 20 which is supplied with fuel through a fuel source shown schematically at 21. A compressor 22 supplies air to the combustor and has a rotor 23 driven by the turbine shaft 19,. The air from the compressor receives heat from the rotary regenerator matrix drum l1 before flowing through the combustor and a discharge 24- from the compressor delivers air to the high pressure, low temperature chamber 12a of the regenerator and the heated air ilows from the regenerator to the combustor through a line 25. The regenerator drum lil is suitably driven in rotation such as by having a drive gear 26 attached thereto driven by a pinion 27. The matrix drum ll is heated in the low pressure high temperature chamber 12b by exhaust gases from the turbine flowing through a line 28 and leaving the regenerator through an exhaust line 29.

The matrix drum lil, as illustrated in FIGURE 3, incorporates an annular matrix 30 formed of a ceramic with how passages therethrough extending in a radial direction. As shown in the enlarged view of FIGURE 4, the ow passages are formed by lirst planar parts 31 and intermediate corrugated parts 32. The planar parts 3i are conveniently in the form of annular ilat surfaced rings and the corrugated parts are also shaped in the form of rings with the corrugations extending radially. The parts are suitably bonded together as at 33 to form a permanent bond and to form substantially triangular radially extending passages for the ilow of gases therethrough.

The cellular ceramic material forming the matrix 30 is identifiable by the following characteristics:

Melting temperature l300 C.2370 C. Specific gravity (25 C.) 1.7-2.6 Mean specific heat (2S-400 C., cal/gr.) 0.24 Linear coefficient of thermal expansion l0-7 (2S-300 C.) 1.0 Thermal conductivity of material (25 C., cgs.)

App. 0.0047

The above material has 'an excellent thermal shock resistance although its mechanical strength is low. This is compensated for by the structure of the entire drum as will be described.

A typical arrangement of parts of theI matrix drum to form the flow openings is such that the average ow opening has a height of 0.045 and a width of 0.095. 20 corrugations per inch are used resulting in flow cells of 400 per square inch. A thickness of material is used so that a ilow area of %80% is obtainable. The web thickness of the material is approximately .005".

A material having the abo-ve properties which has been found suitable to date is offered for sale by Corning Glass Works of Corning, New York under the trade name Cercorj and which is understood to be a ceramic, although it will be understood that other materials having the above characteristics may :also be employed.

The material is well suited in that it has excellent resistance to corrosion of conventional gas turbine combustion gases. It is also attractive because of its low basic cost and mass production.

For rigidifying the matrix material and permitting the attachment of driving mechanism, ceramic rings 34 and abaisse 35 `are suitably attached to the upper and lower surfaces of the matrix at 36 and 37. A preferred means for bonding the rings to the matrix is by the use of a ceramic cement.

The rings are preferably of a material having the same characteristics as the material of the matrix except that the rings are void of passages or in other words, are solid. A material having the above characteristics and which `has proven suitable is `available commercially under the trade name iyroceram This material is solid enabling it to withstand the stresses of steel bands 38 and 39 which are shrunk fit on the outer surfaces of the rings. A feature of the ceramic is its low coeflicient of expansion. Steel bands will have `a .higher coeflicient of expansion and to accommodate this change the bands are shrunk into place so that with heat increase they will not become loose.

The bands are preferably of stainless steel and a 410 stainless steel has proven advantageous. In the method of attaching the bands, a band having an inner diameter smaller than the outer -diameter of the rings is chosen and is heated to substantially 1000 F. and moved over the ring and permitted to cool. The solid ceramic rings are capable of taking the stress of this shrinking force.

The outer surfaces of the steel rings 38 and 39 provide a hard surface for engagement with the supporting rollers and 16. In experiments utilizing the regenerator with a gas turbine 'we have found a pressure differential of 40 lbs. per square inch to exist across the seals. The Hertz stress, or contact stress in the steel bands is an excess of 80,000 lbs. per square inch. The contact stress in the teeth of the drive gear 26, which is also preferably shrunk t on the ceramic ring 35, is approximately 100,000 lbs. per square inch.

During operation, the entire assembly will be heated in excess of 500 F. Because of the large difference in the expansion coecient between the steel and ceramic, the lgear and the steel bands will ordinarily grow more than the ceramic rings and produce a stepped joint at the outside diameter of the drum. However, since the steel members are shrunk onto the ceramic bands, the temperature rise relieves the stress instead of changing dimensions. The magnitude of shrink tit is chosen so that at maximum operating temperature the steel bands and gear are still tight on lthe rings.

Thus it will be seen that we have provided an improved rotary regenerator employing a rotor with the advantages and meeting the objectives set forth above. The material has a low expansion coeicient so that the drum will have practically nov deformation from the extreme radial temperature Igradient which it encounters during operation. Because of this the corresponding regenerator seal design can be simplified and have a lower leakage since straight seal surfaces may be utilized.

The drawings and specification present a detailed disclosure of the preferred embodiments of the invention, and it is to be understood that the invention is not limited to the speci-tic Iform-s disclosed, but covers all modications, changes and alternative constructions and methods falling within the scope of the principles taught by the invention. g f

We claim as our invention:

1`. A rotor for a regenerator comprising, an annular matrix drum formed of a non-corrosive ceramic material with a low expansion coefiicient and a high thermal shock resistance, said drum comprising a series of annular flat surfaced ceramic uninterrupted rings disposed one above the other, an intermediate corrugated ceramic ring disposed between each of said ilat surfaced rings and bonded thereto to form radial passages, annular end rings of solid ceramic material surface bonded to the ends of the drum for expansion and contraction therewith with temperature change, and stressed metal bands surrounding Said end rings and applying a continual inwardly directed force to said ceramic end rings and having smooth annular outer wearing surfaces so that the ceramic end rings are protected.

2 A rotor for a regenerator comprising, an annular matrix drum formed of a non-corrosive ceramic material with a low expansion coefficient and a high thermal shock resistance, said drum comprising a series of annular at surfaced ceramic uninterrupted rings disposed one above the other, an intermediate corrugated ceramic ring disposed between each of said flat surfaced rings and bonded thereto to form radial passages, said ceramic material having a melting temperature of substantially 1300 C., having a mean specific heat in the range of 25-400 C. of 0.24 calories per gram, having a thermal conductivity of 25 C. of 0.0047, and having a linear coefficient of thermal expansion of 1.0 107 in the range of 25 to 300 C., annular end rings of solid ceramic material surface bonded to the ends of the drum for expansion and contraction therewith with temperature change, and stressed metal bands surrounding said end rings and applying a continual inwardly directed force to said ceramic end rings and having smooth annular outer wearing surfaces so that the ceramic end rings are protected.

3. A regenerator mechanism comprising in combination, a regenerator housing, a partition through said housing dividing the housing into a first low temperature chamber and a second high temperature chamber within the housing having an inlet and an outlet for each chamber, an annular matrix drum within the housing extending into each of said chambers and formed of a non-corrosive ceramic material with a low expansion coeflicient and a high thermal shock resistance, said drum comprising a series of annular flat surfaced ceramic uninterrupted rings disposed one above the other, an intermediate corrugated ceramic ring disposed between each of said dat surfaced rings and bonded thereto to form radial passages, annular end rings of solid ceramic material surface bonded to the ends of the drum for expansion and contraction therewith with temperature change, stressed metal bands surrounding said end rings and applying a continual inwardly directed force to said ceramic end rings and having smooth annular outer wearing surfaces for sliding on surfaces within the housing so that the ceramic end rings are protected, seals positioned around the drum at the locations where it passes through the partition, a drive gear attached to one of said metal bands, and a pinion gear in the housing in driving mesh with said drive gear.

References Cited in the le of this patent UNITED STATES PATENTS 1,435,029 Stewart Nov. 7, 1922 2,706,109 Odrnan Apr. 12, 1955 2,747,843 Cox et al May 29, 1956 2,865,611 Bentele Dec. 23, 1958 2,888,248 Bubniak et al May 26, 1959 2,978,227 Hess Apr. 4, 1961 FOREIGN PATENTS 655,313 Great Britain July 18, 1951 

3. A REGENERATOR MECHANISM COMPRISING IN COMBINATION, A REGENERATOR HOUSING, A PARTITION THROUGH SAID HOUSING DIVIDING THE HOUSING INTO A FIRST LOW TEMPERATURE CHAMBER AND A SECOND HIGH TEMPERATURE CHAMBER WITHIN THE HOUSING HAVING AN INLET AND AN OUTLET FOR EACH CHAMBER, AN ANNULAR MATRIX DRUM WITHIN THE HOUSING EXTENDING INTO EACH OF SAID CHAMBERS AND FORMED OF A NON-CORROSIVE CERAMIC MATERIAL WITH A LOW EXPANSION COEFFICIENT AND A HIGH THERMAL SHOCK RESISTANCE, SAID DRUM COMPRISING A SERIES OF ANNULAR FLAT SURFACED CERAMIC UNINTERRUPTED RINGS DISPOSED ONE ABOVE THE OTHER, AN INTERMEDIATE CORRUGATED CERAMIC RING DISPOSED BETWEEN EACH OF SAID FLAT SURFACED RINGS AND BONDED THERETO TO FORM RADIAL PASSAGES, ANNULAR END RINGS OF SOLID CERAMIC MATERIAL SURFACE BONDED TO THE ENDS OF THE DRUM FOR EXPANSION AND CONTRACTION THEREWITH WITH TEMPERATURE CHANGE, STRESSED METAL BANDS SURROUNDING SAID END RINGS AND APPLYING A CONTINUAL INWARDLY DIRECTED FORCE TO SAID CERAMIC END RINGS AND HAVING SMOOTH ANNULAR OUTER WEARING SURFACES FOR SLIDING ON SURFACES WITHIN THE HOUSING SO THAT THE CERAMIC END RINGS ARE PROTECTED, SEALS POSITIONED AROUND THE DRUM AT THE LOCATIONS WHERE IT PASSES THROUGH THE PARTITION, A DRIVE GEAR ATTACHED TO ONE OF SAID METAL BANDS, AND A PINION GEAR IN THE HOUSING IN DRIVING MESH WITH SAID DRIVE GEAR. 